Disclosed is a control valve for flow of solids or fluids which controls flow over a full range and provides a full opening for solids dumping. The control valve includes an orifice plate, a pair of slides disposed adjacent to and downstream of the orifice plate which are relatively moveable toward and away from one another to closed and open positions, and a flow control port in one of the slides which is closed when the slides are in the closed position and which is progressively opened as the slides are moved away from one another. An exit liner is provided downstream of the slides which centers flow after passage through the control port protecting the downstream side of the valve body from serious erosion. Guides for the slides are spaced apart at the center of the flow passage in the valve so that any buildup of solids are cleared on closing the slides. The wear prone parts of the valve are removable from the valve for repair or replacement without removing the valve from the line.